Optical ground tracking apparatus, systems, and methods for use with buried utility locators

ABSTRACT

Methods and apparatus for tracking movement over the ground or other surfaces of a buried utility locator during a utility locate operation are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to co-pendingU.S. Utility patent application Ser. No. 15/728,250, filed Oct. 9, 2017,entitled OPTICAL GROUND TRACKING APPARATUS, SYSTEMS, AND METHODS FOR USEWITH BURIED UTILITY LOCATORS, which is a continuation of and claimspriority to U.S. Utility patent application Ser. No. 13/958,492, nowU.S. Pat. No. 9,784,837, filed Aug. 2, 2013, entitled OPTICAL GROUNDTRACKING APPARATUS, SYSTEMS, AND METHODS, which claims priority under 35U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No.61/790,552, filed Mar. 15, 2013, entitled OPTICAL GROUND TRACKINGAPPARATUS, SYSTEMS, AND METHODS, and to U.S. Provisional PatentApplication Ser. No. 61/679,672, filed Aug. 3, 2012, entitled OPTICALGROUND TRACKING APPARATUS, SYSTEMS, AND METHODS. The content of each ofthese applications is incorporated by reference herein in its entiretyfor all purposes.

FIELD

This disclosure relates generally to apparatus, systems, and methods forlocating hidden or buried objects. More specifically, but notexclusively, the disclosure relates to apparatus, systems, and methodsfor tracking movement over the ground or other surfaces of tools orinstruments or equipment, such as buried object locators or otherdevices, and generating motion, position, location, mapping and/orrelated information for tracked locations, as well as measuring andstoring associated signals and other information detected or generatedduring tracking.

BACKGROUND

With the evolution of more complex infrastructures requiringenhancement, replacement, and expansion in all areas of humanoccupation, and in particular high-density areas such as cities andsuburbs, the ability to accurately map the location of buried conduits,wires and pipelines of various sizes and kinds becomes more pressing, asdoes the need to document actual as-built underground installationsbefore they are covered so that they can be precisely located at a laterdate.

Worker safety and project economic concerns also require the locationand identification of existing underground utilities such as undergroundpower lines, gas lines, phone lines, fiber optic cable conduits, cabletelevision (CATV) cables, sprinkler control wiring, water pipes, sewerpipes, etc., collectively and individually herein referred to as “buriedobjects.”

The unintended destruction of power and data cables may seriouslydisrupt the comfort and convenience of residents and bring hugefinancial costs to business. Therefore human-portable buried objectlocators (also denoted herein for brevity as “locators”) have beendeveloped that sense electromagnetic signals to locate buried utilitiessuch as pipes and cables. Buried objects are frequently located byutility employees or other users by moving a locator over the ground orother surface and receiving and processing electromagnetic signalsemitted from the buried objects. These operations are also known as“line tracing” or “locates.” If the buried conductors carry their ownelectrical signal, they can be traced by detecting the emitted signalsat their corresponding frequency or frequencies, such as 50 or 60 Hz orharmonics thereof for underground power cables. Signals with a knownfrequency may also be applied to pipes and cables via a transmitter andeither directly or inductively or capacitively coupled to enhance theease and accuracy of the line tracing. During these operations, alsoknown as “locates,” it is desirable to track the position and locationof the locator or other device throughout its movement.

Portable utility locators typically carry one or more antennas that areused to detect the electromagnetic signals emitted by buried pipes andcables, and by sondes that have been inserted into pipes. The accuracyof portable utility locators is limited by the sensitivity and theconfiguration of their antennas. Moreover, precise locating of theposition of a locator on the surface of the earth—as would be needed,for example, in order to build an accurate digital map of the locatingresults—has been problematic because of imprecise positioning technologyand an inability to track the position of a locator relative to theground itself.

Accordingly, there is a need in the art to address the above-describedas well as other tracking related problems.

SUMMARY

This disclosure relates generally to ground tracking apparatus, systems,and methods. The apparatus, methods, and systems described herein may beused with a wide variety of tools, instruments, equipment, or otherdevices that move or are moved over the ground or other surfaces.

For example, in one aspect, the disclosure relates to a buried objectlocating system which may include, for example, a buried object locatorand a ground tracking apparatus which may include one or more lightemitting elements, such as light-emitting diodes (LEDs), lasers or otherlight sources, and the like. Embodiments may use light sources andambient light alone in some embodiments and in combination in someembodiments. A plurality of color sensors may be used for capturing andfiltering reflections from such types of emitted light as reflected fromthe ground surface.

In another aspect, the disclosure relates to a method of capturinginformation describing light from a ground surface reflection of emittedlight pulses as digital data and incorporating such data into a mappingprocess.

In another aspect, the disclosure relates to a method for use in aburied object locator system. The method may include, for example,generating, from a locating instrument, laser light in timed pulseswhose reflections may be used by appropriate devices to compute theprecise distance of the locating instrument above the ground. The methodmay further include using such measured distance to refine thecalculated depth of detected buried objects as computed by the locatinginstrument.

In another aspect, the disclosure relates to a locating device equippedwith light-sensing and/or color-sensing arrays which, in combinationwith other locational sensors, such as inertial or gyroscopic sensors,may enable the device to operate as an optical ground-tracking device,capturing situational data for integration with maps and area images.

In another aspect, the disclosure relates to a locating receiver whichmay include a processor or processors for computing surface velocityvectors over ground of the receiver by correlation of reflected lightreceived by a plurality of color sensors, and may also include memorydevices capable of storing and relaying such information in digitalform.

In another aspect, the disclosure relates to a light source that may bea coherent laser light whose reflections from a surface are detected bya sensor from whose input a pattern analysis may be used to deduce therange and motion of the instrument relative to the ground.

In another aspect, the disclosure relates to an optical ground trackingsensor assembly or apparatus. The apparatus may include, for example, anoptical sensor, which may be configured as a perimeter optical sensorarray having a plurality of optical sensor elements. The apparatus mayfurther include an optics assembly for directing light from a surfacearea, such as an area of the ground or other surface, onto the perimeteroptical sensor to generate an image of the surface area. The apparatusmay further include one or more processing elements. The processingelements may be configured to receive an output signal from theperimeter optical sensor array assembly and generate, based at least inpart on the received output signal, information usable to determineposition information associated with the ground tracking apparatus. Theoutput optical signal may be a digital signal representing sensedilluminance and/or color values at optical sensor elements of theoptical sensor array.

The perimeter optical sensor array may be configured, for example, as anoval or circular optical sensor array. Alternately, the perimeteroptical sensor array may be configured as a square or rectangularoptical sensor array. The perimeter optical sensor array may alternatelybe configured as another shape enclosing an area of the substrate, suchas a triangular shape or other shape. The perimeter optical sensor arraymay include a single row of optical sensor elements. The single row ofoptical sensor elements may be disposed substantially around a perimeterof the array or substrate area. Alternately, the perimeter opticalsensor array may include two or more rows of optical sensor elements.The two or more rows may be disposed substantially concentrically arounda perimeter of the array or otherwise arranged in a geometrical fashion.

One or more of the plurality of optical sensor elements of the perimeteroptical sensor array may be color sensors and may provide outputs at twoor more different color wavelengths or bands of color wavelengths.

The optics assembly may be, for example, a reflective optics assemblywhich may be configured similarly to a mirror lens or telescope lens.The reflective optics assembly may include one or more circular mirrorlens assemblies. The reflective optics may include a three dimensional(3D) parabolic reflector. Alternately, the optics assembly may beconfigured as a refractive optics assembly. The refractive opticsassembly may include a refractor lens assembly including an objectivelens.

The processing element may include one or more processor or processingdevices and one or more memories coupled to the processors. Theprocessors and memories may be configured to receive and cross-correlateoutputs of ones of the plurality of optical sensor elements. Thecross-correlation may be performed over samples collected at the samesample time and/or at samples collected at different sample times, suchas at two or more sequential sample times. Based on thecross-correlation the processing element may determine informationusable to determine a position or motion of the ground trackingapparatus based at least in part on the cross-correlated outputs.

The apparatus may further include, for example, a light source orsources configured to generate a controlled light pattern on thesurface. The controlled light pattern may include one or more lines orother shapes. The apparatus may further include a second light sourceconfigured to generate a second controlled light pattern on the surface.The second controlled light pattern may be a line or other shape. Theoutput of the light source may be synchronized with a sampling timeinterval of the optical sensor elements. The controlled light patternmay be pulsed in synchronization with the sampling of the optical sensorelements.

The apparatus may further include, for example, an inertial sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be further based in parton an output signal from the motion sensor. The motion sensor may be anaccelerometer. The accelerometer may provide output information in oneor more axes of motion, such as in three orthogonal axes of motion.

The apparatus may further include, for example, an orientation sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be based in part on anoutput signal from the orientation sensor. The orientation sensor may bea compass sensor or other orientation sensor.

The apparatus may further include, for example, a position sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be further based in parton an output signal from the position sensor. The position sensor may bea global positioning system (GPS) module or other position sensingdevice or module.

The apparatus may further include, for example, an inertial sensorcoupled to the processing element, an orientation sensor coupled to theprocessing element, and/or a position sensor coupled to the processingelement. The information usable to determine a position of the groundtracking apparatus may be based in part on two or more of outputs fromthe inertial sensor, the orientation sensor, and the position sensor.

The apparatus may further include, for example, a distance measurementsensor coupled to the processing element. The distance measurementsensor may provide distance information from the tracking apparatus tothe ground or other surface. The distance measurement sensor may be, forexample, an infrared distance measurement sensor. Alternately, thedistance measurement sensor may be an acoustic distance measurementsensor or other distance measuring device or apparatus.

In another aspect, the disclosure relates to a method of trackingmotion. The method may include, for example, determining, at a perimeteroptical sensor array, a plurality of sample values of receivedillumination, providing the plurality of sample values to a processingelement, performing a cross-correlation, in the processing element, ofones of the plurality of sample values against others of the pluralityof sample values, and determining, in the processing element, positionand/or motion information based at least in part on thecross-correlating. The method may further include storing the determinedposition and/or motion information in a memory. The method may furtherinclude providing the determined distance information on a displaydevice of a coupled buried object locator or other device. The methodmay further include sending the determined distance information toanother device or system, such as a remote database or computer system.

In another aspect, the disclosure relates to a method of trackingmotion. The method may include, for example, determining, at a perimeteroptical sensor array, a plurality of sample values of receivedillumination, providing the plurality of sample values to a processingelement, determining, at the perimeter optical sensor array, anotherplurality of sample values of illumination received at a subsequenttime, providing the another plurality of sample values of illuminationto the processing element, performing across-correlating, in theprocessing element, of ones of the another plurality of sample valuesagainst ones of the plurality of sample values, and determining, in theprocessing element, position and/or motion information based at least inpart on the another cross-correlating. The method may further includestoring the determined additional position and/or motion information ina memory. The method may further include providing the determineddistance information on a display device of a coupled buried objectlocator or other device. The method may further include sending thedetermined distance information to another device or system, such as aremote database or computer system.

In another aspect, the disclosure relates to a perimeter optical sensorarray device. The device may include, for example, a substrate and aplurality of optical sensor elements disposed on or within a perimeterof the substrate.

In another aspect, the disclosure relates to a buried object locatorincluding a ground or surface tracking apparatus. The locator mayinclude, for example, a buried object locator module configured to sensea buried object and generate buried object information correspondingwith the buried object. The surface tracking module may include one ormore sensor arrays which may be configured to detect light reflectedfrom a tracked surface, such as the ground or other surface. The modulemay include a processing module which may be configured to determine orcompute a motion of the buried object locator relative to the trackedsurface, based at least in part on a correlation analysis of lightpatterns associated with the surface. The surface tracking module may befurther configured to generate motion information corresponding with thesensed motion. The locator may further include an integration moduleconfigured to associate the buried object information with correspondingmotion information and store the associated information in a memory.

In another aspect, the disclosure relates to a method of trackingmovement of a device over a surface. The method may include, forexample, generating an output light, providing the output light to thesurface, receiving reflected output light at a perimeter optical sensorarray, and generating information associated with the device movement ina processing element based at least in part on the received reflectedlight.

In another aspect, the disclosure relates to means for implementing theabove-described methods and/or system or device functions, in whole orin part.

Various additional aspects, features, and functionality are furtherdescribed below in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure may be more fully appreciated in connection withthe following detailed description taken in conjunction with theaccompanying drawings, wherein:

FIG. 1A is an isometric view of an embodiment of a locator with anoptical ground-tracking attachment;

FIG. 1B is an isometric view of a locator embodiment similar to theembodiment of FIG. 1A but including a LIDAR apparatus.

FIG. 2 is a partially exploded view of the locator and the opticalground tracking attachment.

FIG. 3 is a perspective view of the locator upper body assembly.

FIG. 4 is a bottom view of the locator upper body assembly of thelocator in FIG. 1A;

FIG. 5 is an exploded view of the outer structure of the tubesubassembly of the optical ground-tracking device of FIG. 1A.

FIG. 6 is a side sectioned view of the optical ground trackingattachment embodiment of FIG. 1A with a schematic illustration of lightray tracing.

FIG. 7 is a bottom view of the optical ground tracking attachmentembodiment of FIG. 1A.

FIG. 8 is a top view of an embodiment of a light-sensor circuit board ofthe optical ground tracker.

FIG. 9 is a cutaway view of the locator and optical ground trackingembodiment illustrating light paths from a laser illumination.

FIGS. 10A & 10B are illustrations of light beams from a laser lightemitter intercepting a sensor array.

FIGS. 11A-11D illustrate various example embodiments of perimeteroptical sensor arrays.

FIG. 12 illustrates details of one embodiment of a process in accordancewith certain aspects for use in tracking movement of a locator or otherdevice over the ground or other surfaces.

FIG. 13 illustrates a block diagram of details of an embodiment of aground tracking apparatus in accordance with certain aspects.

FIG. 14 illustrates details of another embodiment of an optical assemblyin accordance with certain aspects for use in a ground trackingapparatus.

FIG. 15 illustrates details of one embodiment of an optical sensorelement as may be used in various embodiments of perimeter opticalsensor arrays in ground tracking apparatus.

DETAILED DESCRIPTION OF EMBODIMENTS

This application is related to co-assigned United States ProvisionalPatent Application Ser. No. 61/598,312, filed on Feb. 13, 2012, entitledOPTICAL GROUND TRACKING LOCATOR DEVICES AND METHODS, and to U.S.Provisional Patent Application Ser. No. 61/619,327, filed on Apr. 2,2012, entitled OPTICAL GROUND TRACKING APPARATUS, SYSTEMS AND METHODS.In addition, the various aspects and details described herein may beused in combination with the disclosures of the following co-assignedpatent applications in various buried object locator device and/orrelated device or system embodiments. These co-assigned applicationsinclude U.S. patent application Ser. No. 10/268,641, entitledOMNIDIRECTIONAL SONDE AND LINE LOCATOR, filed on Oct. 9, 2002, U.S.patent application Ser. No. 11/970,818, entitled MULTI-SENSOR MAPPINGOMNIDIRECTIONAL SONDE AND LINE LOCATORS, filed on Jan. 8, 2008, U.S.patent application Ser. No. 12/016,870, entitled RECONFIGURABLE PORTABLELOCATOR EMPLOYING MULTIPLE SENSOR ARRAY HAVING FLEXIBLE NESTEDORTHOGONAL ANTENNAS, filed Jan. 18, 2008, U.S. patent application Ser.No. 11/077,947, entitled SINGLE AND MULTI-TRACE OMNIDIRECTIONAL SONDEAND LINE LOCATORS AND TRANSMITTER USED THEREWITH, filed on Mar. 11,2005, U.S. Patent Application 61/485,078, entitled LOCATOR ANTENNACONFIGURATION, filed on May 11, 2011, and U.S. patent application Ser.No. 13/469,024, entitled BURIED OBJECT LOCATOR APPARATUS AND SYSTEMS,filed May 10, 2012. The content of each of the above-describedapplications is hereby incorporated by reference herein in its entirety.The above applications may be collectively denoted herein as the“co-assigned applications” or “incorporated applications.”

The present disclosure relates generally to apparatus, systems, andmethods for locating hidden or buried objects and tracking locationand/or movement during location or other operations. More specifically,but not exclusively, the disclosure relates to buried object locatingreceivers and processing devices for receiving signals generated fromthe buried or hidden objects and processing the signals to generateinformation for user output and/or storage, along with trackingapparatus and methods for tracking position and/or movement over theground or other surface, and mapping apparatus and methods forgenerating mapping information associated with the tracking and locatorsignals.

As used herein, the term “buried objects” includes objects locatedinside walls, between floors in multi-story buildings or cast intoconcrete slabs, for example, as well as objects disposed below thesurface of the ground. In a typical application a buried object is apipe, cable, conduit, wire, or other object buried under the groundsurface, at a depth of from a few centimeters to meters or more, that auser, such as a utility company, construction company, homeowner, orothers want to locate, map (e.g., by surface position as defined bylatitude/longitude or other surface coordinates, and/or also by depth),and/or provide a surface mark using paint.

When locating hidden or buried objects or using other devices that aremoving or moved over the ground or other surfaces, an operator may beable to store and map detections made during a locate or other operationto provide efficient operation. Thus, locating devices or other devicescapable of coordinating GPS signals or local terrain characteristicswith the signals received from buried objects allow operators to moreprecisely fix the location of those objects on maps or overlaid ontobird's-eye or satellite images, for example, and to more readily recoverthe history of past locates in a given location. Precisely fixing thephysical location of a locator device at a given moment in time candepend on GPS or wireless signals, the inputs from onboard inertialsensors, and the recording of ground characteristics and terrainfeatures in the immediate vicinity by means of cameras or other opticaldevices. However, GPS devices have coverage gaps and can be affected bysignal attenuation, interference, and propagation effects such asmultipath. Therefore, signals are not always reliable or available tomeasure motion and track position or location. In addition, otherdevices, such as inertial navigation devices such as accelerometers, aresubject to drift and other distortions. As described herein, additionaltracking data and information may be obtained by optical sensingtechniques as described herein, and these may be combined with GPS,inertial, wireless, or other location or position-determining mechanismsto improve locator device performance, increase efficiency, and/orprovide additional data or information for mapping or otherapplications.

For example, in one aspect, the present disclosure relates to a utilitylocating device and associated optical tracking apparatus for trackinglocation over the ground while locating and capturing opticalcharacteristics of the ground surface (such as brightness/illuminance,color, texture, and/or other surface features) as data for use inintegrating the locator's electromagnetic detections with terrestrialmapping satellite images, blueprints, photographs, and/or other data orinformation.

In another aspect, a locator and associated tracking apparatus may beconfigured to detect the variable reflectivity or coloration of groundsurface, including markings laid on the ground and/or projected onto it,and occasional encountered objects lying on the ground. To accomplishthis, a highly directional LED light source and/or a laser light sourcemay be optionally combined with a near-range light or color sensorarray. A laser light source may be coupled to a diffraction grating orother imaging mechanism to generate lines or other shapes on the groundwhich may then be optically sensed and processed to determineinformation such as motion, height above the ground, tilt, and the like.One or more laser light sources may be used to provide a contrastingreflection which may be analyzed to provide a high-precision calculationof height above ground, orientation and/or movement over ground of thelocator.

In another aspect, the disclosure relates to a buried object locatingreceiver with a ground tracking apparatus. The receiver may, forexample, be equipped with sensors designed to receive reflected lightfrom a ground surface over which the locator receiver is held and may beequipped with analog-to-digital circuitry enabling the values ofreceived light to be stored as digital data. The receiver may also beequipped with distance measurement sensors designed to emit light atknown frequencies and sense reflections of such light from a groundsurface and further to calculate the distance of the sensor from thereflecting surface. In another aspect, parabolic or spherical mirrorsand lenses may be used to focus reflected light toward light sensors, orrefractive optical elements may be similarly used. A processing elementmay be included to process received data by performing correlationsand/or other signal processing functions on received optical sensordata.

In another aspect, the receiver may be equipped with a controlled lightsource, such as a laser emitter or other light output device, along witha detector which receives reflections of the emitted coherent light froma ground surface. The pattern of the reflections of coherent light maybe analyzed in a processing element to determine the direction andvelocity of movement relative to the ground surface.

In one aspect the disclosure relates to an optical ground trackingsensor assembly or apparatus. The apparatus may include, for example, anoptical sensor, which may be configured as a perimeter optical sensorarray having a plurality of optical sensor elements. The apparatus mayfurther include an optics assembly for directing light from a surfacearea, such as an area of the ground or other surface, onto the perimeteroptical sensor to generate an image of the surface area. The apparatusmay further include one or more processing elements. The processingelements may be configured to receive an output signal from theperimeter optical sensor array assembly and generate, based at least inpart on the received output signal, information usable to determineposition information associated with the ground tracking apparatus. Theoutput optical signal may be a digital signal representing sensedilluminance and/or color values at optical sensor elements of theoptical sensor array.

The perimeter optical sensor array may be configured, for example, as anoval or circular optical sensor array. Alternately, the perimeteroptical sensor array may be configured as a square or rectangularoptical sensor array. The perimeter optical sensor array may alternatelybe configured as another shape enclosing an area of the substrate, suchas a triangular shape or other shape. The perimeter optical sensor arraymay include a single row of optical sensor elements. The single row ofoptical sensor elements may be disposed substantially around a perimeterof the array or substrate area. Alternately, the perimeter opticalsensor array may include two or more rows of optical sensor elements.The two or more rows may be disposed substantially concentrically arounda perimeter of the array or otherwise arranged in a geometrical fashion.

One or more of the plurality of optical sensor elements of the perimeteroptical sensor array may be color sensors and may provide outputs at twoor more different color wavelengths or bands of color wavelengths.

The optics assembly may be, for example, a reflective optics assemblywhich may be configured similarly to a mirror lens or telescope lens.The reflective optics assembly may include one or more circular mirrorlens assemblies. The reflective optics may include a three dimensional(3D) parabolic reflector. Alternately, the optics assembly may beconfigured as a refractive optics assembly. The refractive opticsassembly may include a refractor lens assembly including an objectivelens.

The processing element may include one or more processor or processingdevices and one or more memories coupled to the processors. Theprocessors and memories may be configured to receive and cross-correlateoutputs of ones of the plurality of optical sensor elements. Thecross-correlation may be performed over samples collected at the samesample time and/or at samples collected at different sample times, suchas at two or more sequential sample times. Based on thecross-correlation the processing element may determine informationusable to determine a position or motion of the ground trackingapparatus based at least in part on the cross-correlated outputs.

The apparatus may further include, for example, a light source orsources configured to generate a controlled light pattern on thesurface. The controlled light pattern may include one or more lines orother shapes. The apparatus may further include a second light sourceconfigured to generate a second controlled light pattern on the surface.The second controlled light pattern may be a line or other shape. Theoutput of the light source may be synchronized with a sampling timeinterval of the optical sensor elements. The controlled light patternmay be pulsed in synchronization with the sampling of the optical sensorelements.

The apparatus may further include, for example, an inertial sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be further based in parton an output signal from the motion sensor. The motion sensor may be anaccelerometer. The accelerometer may provide output information in oneor more axes of motion, such as in three orthogonal axes of motion.

The apparatus may further include, for example, an orientation sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be based in part on anoutput signal from the orientation sensor. The orientation sensor may bea compass sensor or other orientation sensor.

The apparatus may further include, for example, a position sensorcoupled to the processing element. The information usable to determine aposition of the ground tracking apparatus may be further based in parton an output signal from the position sensor. The position sensor may bea global positioning system (GPS) module or other position sensingdevice or module.

The apparatus may further include, for example, an inertial sensorcoupled to the processing element, an orientation sensor coupled to theprocessing element, and/or a position sensor coupled to the processingelement. The information usable to determine a position of the groundtracking apparatus may be based in part on two or more of outputs fromthe inertial sensor, the orientation sensor, and the position sensor.

The apparatus may further include, for example, a distance measurementsensor coupled to the processing element. The distance measurementsensor may provide distance information from the tracking apparatus tothe ground or other surface. The distance measurement sensor may be, forexample, an infrared distance measurement sensor. Alternately, thedistance measurement sensor may be an acoustic distance measurementsensor or other distance measuring device or apparatus.

In another aspect, the disclosure relates to a method of trackingmotion. The method may include, for example, determining, at a perimeteroptical sensor array, a plurality of sample values of receivedillumination, providing the plurality of sample values to a processingelement, performing a cross-correlation, in the processing element, ofones of the plurality of sample values against others of the pluralityof sample values, and determining, in the processing element, positionand/or motion information based at least in part on thecross-correlating. The method may further include storing the determinedposition and/or motion information in a memory. The method may furtherinclude providing the determined distance information on a displaydevice of a coupled buried object locator or other device. The methodmay further include sending the determined distance information toanother device or system, such as a remote database or computer system.

The method may further include, for example, determining, at theperimeter optical sensor array, another plurality of sample values ofillumination received at a subsequent time, providing the anotherplurality of sample values of illumination to the processing element,performing another cross-correlating, in the processing element, of onesof the another plurality of sample values against ones of the pluralityof sample values, and determining, in the processing element, additionalposition and/or motion information based at least in part on the anothercross-correlating. The method may further include storing the determinedadditional position and/or motion information in a memory. The methodmay further include providing the determined distance information on adisplay device of a coupled buried object locator or other device. Themethod may further include sending the determined distance informationto another device or system, such as a remote database or computersystem.

In another aspect, the disclosure relates to a method of trackingmotion. The method may include, for example, determining, at a perimeteroptical sensor array, a plurality of sample values of receivedillumination, providing the plurality of sample values to a processingelement, determining, at the perimeter optical sensor array, anotherplurality of sample values of illumination received at a subsequenttime, providing the another plurality of sample values of illuminationto the processing element, performing across-correlation, in theprocessing element, of ones of the another plurality of sample valuesagainst ones of the plurality of sample values, and determining, in theprocessing element, position and/or motion information based at least inpart on the another cross-correlating. The method may further includestoring the determined additional position and/or motion information ina memory. The method may further include providing the determineddistance information on a display device of a coupled buried objectlocator or other device. The method may further include sending thedetermined distance information to another device or system, such as aremote database or computer system.

In another aspect, the disclosure relates to a perimeter optical sensorarray device. The device may include, for example, a substrate and aplurality of optical sensor elements disposed on or within a perimeterof the substrate.

The optical sensor elements may be disposed, for example, in a circularconfiguration on the substrate or around an enclosed area of thesubstrate. The optical sensor elements may be disposed in a rectangularconfiguration on the substrate or around a square or rectangularenclosed area of the substrate. The optical sensor elements may bedisposed in a triangular configuration on the substrate or around atriangular or other-shaped area of the substrate. The device may furtherinclude one or more additional optical sensor elements disposed in partof an interior area of the substrate enclosed by the perimeter opticalsensor elements.

The optical sensor elements may be, for example, color sensor elements.The color element sensors may be configured to generate signalscorresponding to receive illuminance in one or more wavelengths orranges or bands of wavelengths.

In another aspect, the disclosure relates to a buried object locatorincluding a ground or surface tracking apparatus. The locator mayinclude, for example, a buried object locator module configured to sensea buried object and generate buried object information correspondingwith the buried object. The surface tracking module may include one ormore sensor arrays which may be configured to detect light reflectedfrom a tracked surface, such as the ground or other surface. The modulemay include a processing module which may be configured to determine orcompute a motion of the buried object locator relative to the trackedsurface, based at least in part on a correlation analysis of lightpatterns associated with the surface. The surface tracking module may befurther configured to generate motion information corresponding with thesensed motion. The locator may further include an integration moduleconfigured to associate the buried object information with correspondingmotion information and store the associated information in a memory.

The buried object locator may, for example, be further configured togenerate a controlled light output such as a tracking light pulse orbeam, and transmit the tracking light pulse or beam to the trackedsurface. The locator may be further configured to generate a map of theburied object relative to the surface. The map may be generated based atleast in part on the buried object information and the motioninformation. The locator may be further configured to provide a visualdisplay of the buried object information and corresponding motioninformation, such as on a visual display of the locator or other displaydevices. The processing element or other control elements may beconfigured to control a light output of at least one output lightgenerator assembly.

In another aspect, the disclosure relates to a method of trackingmovement of a device over a surface. The method may include, forexample, generating an output light, providing the output light to thesurface, receiving reflected output light at a perimeter optical sensorarray, and generating information associated with the device movement ina processing element based at least in part on the received reflectedlight.

The output light may, for example, be generated from an LED assembly.The output light may be provided from a laser light emitter and may beprovided to the perimeter optical sensor from a reflector. The reflectormay be a three dimensional (3D) parabolic reflector. The optical sensorarray may include a plurality of sensor elements, which may be digitaloutput color sensor elements. The information associated with devicemovement may be location or tracking information. The location ortracking information may be generated in a processing element. Theprocessing element may be configured to receive one or more signals fromthe input light sensor assembly and generate, based at least in part onthe received signals, the location or tracking information.

The method may further include, for example, controlling, from theprocessing element or other control element, the generated output light.The output light may be controlled in coordination or synchronizationwith sampling of the light at the perimeter optical sensor array. Theoutput light may be pulsed or otherwise modulated. The output lightamplitude and/or color or wavelengths may be varied. The light amplitudeand/or color wavelengths may be varied in coordination orsynchronization with sampling of the received light at the perimeteroptical sensor array. Multiple sensor elements may be cross-correlatedon a many-to-many comparison process to perform height and/or locationcalculations.

In another aspect, the disclosure relates to one or more computerreadable media including non-transitory instructions for causing acomputer to perform the above-described methods or functions, in wholeor in part.

In another aspect, the disclosure relates to apparatus and systems forimplementing the above-described methods or functions, in whole or inpart.

It is noted that the following exemplary embodiments are provided forthe purpose of illustrating examples of various aspects, details, andfunctions of apparatus, methods, and systems for locating buried orhidden objects; however, the described embodiments are not intended tobe in any way limiting. It will be apparent to one of ordinary skill inthe art that various aspects may be implemented in other embodimentswithin the spirit and scope of the present disclosure.

As used herein, the term, “exemplary” means “serving as an example,instance, or illustration.” Any aspect, detail, function,implementation, and/or embodiment described herein as “exemplary” is notnecessarily to be construed as preferred or advantageous over otheraspects and/or embodiments.

Referring to FIG. 1A, an embodiment of a buried object locator 100 withan optical tracking assembly/apparatus 102, in accordance with certainaspects, is illustrated. The locator may be any embodiment of anelectromagnetic locating device for locating buried or hidden objects,such as the locator devices described in the incorporated co-assignedapplications or other similar or equivalent locating devices.Electromagnetic locators typically include one or more magnetic fieldantennas which may each be single antennas or antenna arrays. In theexample locator embodiment 100 of FIG. 1A, three antennas 122, 124, and126 are shown disposed on an antenna mast 130, however, other locatorembodiments may include fewer or more antennas and/or alternate antennaconfigurations. In embodiments of other devices where a similar groundtracking apparatus may be used, other components and/or configurationsmay replace the antennas and associated elements as are used in buriedobject locators while still benefiting from ground or surface trackingfunctionality as described herein.

A control module 140 may be coupled to or atop the mast 130 as shown inFIG. 1A and may be part of an upper body assembly 104 as shown. Thecontrol module 140 may include elements including one or moreelectronics modules, one or more processing elements or modulesincluding processors, memory, and related components, one or moredisplays, such as an LCD display or other display elements, userinterface elements such as switches, actuators, knobs, mice, joysticks,audio input or output devices, and/or other user interface elements. Inan exemplary embodiment the control module 140 may be configured toreceive signals from the antennas and determine position informationassociated with buried objects, such as location relative to the groundor other surface, depth, current flow and/or direction, and the like.

In addition, locator 100 may include an optical ground tracking assembly102, which may be fixed or, in an exemplary embodiment, removablyattached to the upper body assembly 104 of the locator 100 such as shownin FIG. 1A. The locator 100 may, in an exemplary embodiment, be a devicesuch as described in U.S. patent application Ser. No. 13/469,024,entitled BURIED OBJECT LOCATOR APPARATUS AND SYSTEMS, filed on May 10,2012, which is incorporated herein by reference. A bracket 106 or othercoupling mechanism (not shown) may attach the lower end of the opticalground tracking assembly 102 to the antenna mast or one of the antennashells of the locator 100.

A distance measuring element to determine the distance from a referencepoint on the locator or ground tracking assembly may be disposed on theground tracking apparatus or locator. For example, an infrared distancemeasuring sensor 108 may optionally be attached to the outside of theoptical ground tracking apparatus 102 or elsewhere on or within theground tracking assembly or locator to perform optical sensing. Thedistance measuring sensor may be a device such as, for example, aGP2Y0A02YKF sensor unit available from SHARP Microelectronics of Camas,Wash. or other distance measuring devices. If an optical sensor is used,the light emitter of the distance measuring sensor may project infraredlight over a projection region 110 and then determine the distance tothe ground or other surface from the sensor unit. The optical groundtracking assembly 102 may include exterior containers or projections 112in which controlled light sources, such as laser light sources and LEDlight sources, for example, may be mounted. These light sources may beused to provide controlled lighting, such as pulsed lights, directionallight beams or shapes, or other controlled light features to the groundor other surface during operation.

In an exemplary embodiment, an optical ground tracking device may beconstructed in a housing or case having a substantially cylindricalshape using, for example, a single tubular housing 114 or otherstructural housing, which may include an electronic connection, such as,for example, a USB connector and plug, which may electrically couple theground tracking device to a processing element or electronics modulewhich may be on a circuit board or other circuit assembly in the body oflocator 100, such as in control module 140 as shown. Alternately shapesand configurations of housings, such as square or rectangular-shapedtubes or housings or other shapes (such as ovals, rounder cornerrectangular shapes, etc.) may also be used in other embodiments.

In some embodiments a ground tracking apparatus processing element orelements may be disposed within the ground tracking apparatus, such aswithin assembly 102 as shown. Alternately, or in addition, processingelements for performing the ground tracking processing functionalitydescribed herein may be housed within the locator (or other device),such as in control module 140.

Additional sensors, mechanisms, and apparatus may be used in conjunctionwith a ground tracking apparatus and/or locator with a ground trackingapparatus in keeping with the present disclosure. For example, asillustrated in FIG. 1B, a locator embodiment 150 which may be similar tothe locator embodiment 100 of FIG. 1A with the addition of a lightdetection and ranging (LIDAR) apparatus 160, a upward facing verticallyoriented camera 170, a laser range finder mechanism 180, and a laserDoppler apparatus 190 is illustrated. The LIDAR apparatus 160 may allowfor measuring of height and distance from the ground surface. The LIDARapparatus 160 may further create a 3D point cloud. The camera 170 may beused for sun position tracking as well as to view and record the user.The laser range finder mechanism 180 may be used to measure the heightof the device off the ground on one or more locations. The laser Dopplerapparatus 190 may be used to measure over ground velocity, and/or speed,and/or direction. Numerous other sensors, mechanisms, and apparatusesthat may be used in conjunction with a ground tracking apparatus and/orlocator with a ground tracking apparatus in keeping with the presentdisclosure may be readily apparent to those skilled in the art.

Referring to FIGS. 2 and 3, the upper body assembly 104/control module140 may include user interface elements such as a display screen 202, acontrol panel 204, as well as a battery dock 206, and a handle 208assembled on or within a locator housing 210. A Universal Serial Bus(USB) connector 212 may be used to electrically connect the opticalground tracking assembly 102 to the upper body assembly 104, and may besupported by screws 214 or other attachment mechanisms. In an exemplaryembodiment USB interfacing may be used to provide data between thelocator and ground tracking apparatus, however, in other embodimentsalternate signaling mechanisms may be used, such as other serial buses,parallel data buses, wireless connections, optical connections, and thelike.

Locator 100 may include an intelligent battery, along with associateddocking and interface circuitry such as described in, for example,co-assigned U.S. patent application Ser. No. 13/532,721, entitledMODULAR BATTERY PACK APPARATUS, SYSTEMS, AND METHODS, filed Jun. 25,2012, the content of which is incorporated by reference herein. Thecontrol module 140 and/or other modules or processing elements in thelocator may include intelligent battery functionality and viral dataand/or code transfer functionality such as is described in the '721application and in co-assigned U.S. Patent Application Ser. No.61/663,617, entitled MODULAR BATTERY PACK APPARATUS, SYSTEMS, ANDMETHODS INCLUDING VIRAL DATA AND/OR CODE TRANSFER, the content of whichis incorporated by reference herein.

Referring to FIG. 4, details of the upper body assembly 104 of locatorembodiment 100 is illustrated from below. A USB socket 402 may bedisposed on or within the upper body assembly 104, such as by beingformed into the base of upper body assembly 104. The USB socket may beconfigured to provide a connector to electrically attach the opticalground tracking assembly 102 (FIG. 1A) to the locator 100 (FIG. 1A). Inalternate embodiments other wired or wireless data connection circuitryand configurations may also be used. The upper body assembly 104 may beformed with an indentation 404 on either side to which the opticalground tracker assembly 102 (FIG. 1A) may be attached mechanically, forexample, by using support screws 214 or other attachment mechanisms. Inalternate embodiments, various other fixed or detachable mechanisms maybe used to secure, either fixedly or removably, the ground trackingapparatus 102 to the locator 100 or to other devices to which it iscoupled.

Turning to FIG. 5, an exploded view of an exemplary optical groundtracker tube subassembly 500 with reflective optics is shown. In anexemplary embodiment, a USB connection may be used to electricallycouple the ground tracker assembly 102 to the locator 100 to providesignal connectivity. For example, a USB plug 212 may be seated so as toprotrude from the upper end of the tube subassembly 500 and allowconnection of a USB cable between the subassembly 500 and locator 100. Amounting cap 504 may be formed so as to support the USB plug 212 and mayfurther be formed, for example, with mounting lobes 506 sized to attachto the indentations (404 in FIG. 4) in the upper body assembly (104 inFIG. 2). Although the illustrated embodiment is shown in a cylindrical,circular cross-sectioned configuration, other shapes, such as square,oval, rectangular or other cross sectional tubes, as well as tubes ofvarying cross-sectional shape and/or sizes may be used in alternateembodiments.

An inner mount shell 508 may be seated with an O-ring 514 to the mountcap 504 by threading or other attachment mechanisms. A tubular housing114 may be formed of carbon fiber, for example, or other lightweightmaterials, and may be joined to the inner mount shell 508 by threadingor other attachment mechanisms. The junction between the tubular housing114 and the mount inner shell 508 may be sealed for protection, forexample, by use of a sealing element, such as a tape seal 512 or othersealing mechanisms. A printed circuit board (PCB) 516 may be mountedbelow the mounting cap. Position, location, motion and/or orientationsensors may be mounted, such as a 9-axis Invensense MPU-6000 combinationgyroscope and accelerometer MEMS unit, for example, with a combinedmagnetometer on the printed circuit board or elsewhere in the groundtracking assembly to provide motion, position, orientation, and/orlocation information to be used as described subsequently herein ingenerating tracking information. Other motion sensors and orientationsensors may also be used in various embodiments, such as, for example,compass sensors, multi-axis accelerometers, GPS modules, wirelessmodules, and the like.

In some embodiments reflective optics as shown in FIG. 5 may be used todirect light for imaging the ground or other surfaces. For example, anoptical ground tracker assembly may include an optical reflector, suchas a reflective, curved optical-grade mirror such as reflecting mirror518 as shown, or other mirror or reflective elements. The reflectingmirror 518 may be positioned and aligned to reflect incident rays oflight onto a sensor array. Such a reflector may, for example, beconstructed of optically coated glass and/or other reflector materials.

A wire harness 520, or other conductor configurations, may be used toelectrically connect the PCB with other circuit boards and correspondingconnectors and circuit elements on the locator 100 (FIG. 1A).

An optical light-sensor assembly may be positioned within the opticalground tracker to receive light from a surface of interest. For example,a perimeter light sensor array 522 may be centrally located along theaxis of the tubular housing 114 such that incident light is reflectedfrom the reflecting mirror 518 onto the sensor assembly 522. Asdescribed subsequently with respect to FIGS. 11A-11D, the perimeterlight sensor array includes a plurality of light sensing elementsarranged around the perimeter or other enclosed area of a sensorsubstrate to sense received light. Additional sensor elements within theenclosed area may also optically be included on the sensor array toprovide additional sensing data.

In operation, as the locator or other instrument, along with the groundtracking apparatus, moves over the ground or other surface the perimeterlight sensor array elements sense movement of features, with the sensedinformation then processed by cross-correlation and/or other processingtechniques to determine motion/position information. Examples of thisare described subsequently herein. By reducing the number of sensingelements from a full grid or array to a subset including perimetersensing elements, and, optionally some interior sensing elements,processing requirements such as for performing cross-correlations may begreatly reduced from performing similar processing over an entire gridof sensor elements.

Turning to FIG. 6, an embodiment of an optical ground tracker tubesubassembly 500 using reflective optics is illustrated in cross-section.Within a tubular housing 114 a support platform 602 may be formed whichmay, for example, consist of a central island, which may be configuredin an approximately circular form in an exemplary embodiment and may besupported by three formed arms or other support structures. A sensorassembly 522 may be mounted to the support platform 602 using a supportblock 606 or other attachment mechanism. An adjusting screw 608 or otheradjustment mechanism may be used for calibration and fine tuning. Inalternative embodiments the sensor assembly 522 may be fixed in positionrelative to a reflecting mirror 518.

The reflecting mirror 518 may be retained or attached, for example, ator near the top of the tubular housing 114. The disposition of thereflecting mirror 518 and the sensor assembly 522 may be designed suchthat incident light ray 610, light ray 612, and light ray 614, forexample, will each be reflected so as to impact a corresponding sensorarea on the sensor assembly 522. It will be appreciated that theseexemplary rays are illustrative only, and that in actual use, incidentrays of light may arrive from all directions and be reflected by thecurved reflecting mirror 518 so as to impact some part of a circulararray of sensors on the sensor assembly 522. Although FIG. 6 illustratesan exemplary reflective optics configuration, in alternate embodimentsrefractive optics, such as are shown in the example embodiment of FIG.14, may also be used.

Turning to FIG. 7, an exemplary design of a support platform (602 inFIG. 6) for the perimeter sensor array 522 is shown in a planar view. Inthe interior of the tubular housing (114 in FIG. 5), a plurality ofmolded arms 704 may be formed to support central formed platform 602with a central threaded opening 706 which may, for example, retain thethreaded adjustment screw (608 in FIG. 6). The reflecting mirror 518(FIG. 5) may be so seated or attached as to be coaxial with the supportplatform 602 and the sensor assembly (522 in FIG. 5). Other mounting andcalibration mechanisms may also be used in alternate embodiments toposition the perimeter sensor array relative to a reflecting mirror.

Turning to FIG. 8, details of the perimeter sensor array assemblyembodiment 522 are illustrated. In an exemplary embodiment the sensorarray includes a substrate, such as a printed circuit board (PCB) 804,supporting an array 802 of sensor elements 806 arranged around theperimeter or other enclosed area of the substrate. Sensor array 802 maybe a sensor array of ones of a plurality of individual color sensorelements 806 such as, for example, are included in the Texas AdvancedOptoelectronic solutions TCS3404, manufactured by Texas AdvancedOptoelectronic solutions (TAOS) of Plano, Tex., or other multi-colorelement sensor arrays. The color sensors 806 may be disposed around theperimeter of the sensor PCB 804 as shown to enclose an area on which acorresponding area of the ground or other surface is to be imaged. In anexemplary embodiment, forty separate sensor elements 806 may comprisethe sensor array 802, however, other numbers, types, shapes, and/orarrangements of sensor elements may be used in various configurations.

The TCS3404, for example, is a 16-bit sensor which produces data on red,green, blue and clear color values. The TCS3404 digital color lightsensors derive color chromaticity and luminance (intensity) of ambientlight and provide a digital output with 16-bits of resolution. Theindividual sensors may include, for example, an 8×2 array of filteredphotodiodes, analog-to-digital converters, and control functions on asingle monolithic CMOS integrated circuit. Of the sixteen photodiodes,for example, four may have red filters, four may have green filters,four may have blue filters, and four may have no filter (clear), in anexemplary design. The TCS3404 digital color light sensor furthersupports a synchronization function enabling it to be synchronized withpulsed light if desired. Additional details of this sensor element arefurther illustrated in FIG. 15. While the TAOS sensors may be used in anexemplary embodiment, other sensor types and sensor configurations maybe used in various embodiments. For example, alternative arrangements ofsensors, sensor types, and different numbers of sensors may be used invarious embodiments.

In another aspect, controlled light, such as a laser light source orother controlled light source, may be used to augment the precision ofpositional computation by an optical or optical-mechanical groundtracking apparatus such as described herein. In another aspect, othersources of illumination, such as an array of LEDs or other visible, IR,and/or UV light sources may be used to augment ambient light used in theoptical ground tracking process. Controlled lighting may be shaped inthe form of projected lines or other shapes, such as through use of adiffraction grid or other mechanism, and may be pulsed or otherwisemoduled in conjunction with sensing done at the perimeter sensor arrayor other elements of the ground tracking apparatus.

Turning to FIG. 9, an embodiment of an optical ground tracking locatingsystem 900 with controlled lighting, such as a plurality of laserillumination units 904, which may be positioned on or within theexterior surface of the optical ground tracking device 902, isillustrated. A plurality of LED illumination units 906 may be similarlymounted to augment ambient light in the optical ground tracking process.The laser units 904 may be so disposed that, for example, one laser unitmay project a line 908 in red light, for example, and the other mayproject a separate line 910 of red light along the ground. Otherfrequency lasers, such as green-light-emitting lasers, or other colorsor combinations of colors may also be used.

The length of the line 908 and the line 910, and the apparent distanceof line 908 from line 910, will vary with the height above ground of thelocator 900 at any given moment. The reflected light from line 908 andfrom line 910 will intercept different individual color sensors 806(FIG. 8) in the circular color sensor array 802 (FIG. 8) and willproduce different signals in different individual sensors 806 (FIG. 8).A comparative algorithm may be encoded as instructions stored on acomputer-readable media and may be implemented in a processing elementin the locator and/or ground tracking device. The comparative algorithmmay perform cross-correlations by rapidly comparing the values of eachsensor 806 (FIG. 8) with those of each other sensor 806 (FIG. 8) in thesensor array 802 (FIG. 8) for a given moment in time to determinerelative distance information. In addition, information regarding tiltsor other shifts in orientation may also be performed by similarprocessing based on points of intersection of the line with theperimeter array sensor elements. In other embodiments different shapesmay alternately be projected onto the ground or other surface from thelight source and correspondingly processed.

A calibration of the locator system 900 may be used which enables thesystem to derive precise height above ground of the locator 900 at anyinstant based on the cross-correlation of color values, and the locationand angle of separation of those sensors where different color values,including peak red-filter values, have been recorded. A single laserprojection will produce two such computable elevation points; duallasers may be used as in FIG. 9 to produce four computable elevationpoints, thus enabling the derivation of angle or attitude of thelocating unit at a given instant. More than two laser units 904 may beused, for example, to produce a variety of formed light patterns forreflection. Additional supplementary optics 912 in the form, forexample, of a fitted light lens, may be attached to the tubular housing114 to guide and/or form incident light beams or light beams reflectedfrom a ground surface, for example. Alternative supplementary opticdesigns may be used, such as, for example, smaller lenses mounted on theinner circumference of the tubular housing 114.

In one aspect of the present disclosure, a locator may electronicallyperform onboard processing to derive velocity and height measurementfrom the values returned by multiple color sensors of the perimetersensor array. In such processing the signal from each color sensor maybe measured as a function of time. Signal data from every color sensorin sensor array 802 (FIG. 8) may be cross-correlated with signal datafrom every other color sensor for a given point in time. Samples may betaken sequentially in time and then cross-correlated across timeoffsets. In some embodiments, sample rate may be adjusted based onadditional received information, such as motion information received byother sensors such as inertial, compass, GPS, or other sensors.

For each cross-correlation, there is a peak value at some time offset,τ_(ij). There is likewise a spacing vector between each color sensor,{right arrow over (δ_(ij))}. For each sensor triple, a velocity vectormay be found that depends on the location of the sensors. For example,if the first sensor is at the origin, the second sensor at δ^(ŷ) and thethird sensor at +δ^({circumflex over (x)}), then, it can be shown that:tan

θ=τ₁₃/τ₁₂

The angle θ is the angle between the direction of motion and they axis.The magnitude of the velocity vector may be found from:

$v = {\frac{\delta}{\tau_{13}}\sin\theta}$

Similar equations may be determined for different geometries of sensorssuch as the forty-sensor array in FIG. 8, for example.

Turning to FIGS. 10A and 10B, the use of formed light patterns such aslaser light line 908 (FIG. 9) and laser light line 910 (FIG. 9) may beused to interpolate the calculated height of a locator above ground.

In FIG. 10A the impact of reflected light from laser light lines 908 and910 is shown in a first position as the reflected light strikes thesensor array 802. The correlation of each sensor's output on four colorchannels (red, blue, green and clear) with the output from every othersensor in the array 802 will yield a unique composite digital profilefor this event. In FIG. 10B the impact of reflected light from laserlight lines 908 and 910 is shown in a second position as the reflectedlight strikes the sensor array 802. It will be appreciated that thelaser light lines 908 and 910 are further apart in FIG. 10B than theyare in FIG. 10A, and strike different components of the sensor array802. The difference in the relative positions of laser light line 908and laser light line 910 in FIG. 10B (compared to FIG. 10A) may beattributable to the locator (and the light emitters) being at a greaterheight above the reflecting surface. As a result of cross correlationbetween all the sensors comprising the sensor array 802, this differencemay be precisely quantified in comparing the unique composite digitalprofiles of the two events illustrated.

In another aspect, color sensors may be combined with inertial,gyroscopic, and compass sensors to refine location measurement. In anexemplary embodiment, such orientation and motion sensors may beintegrated into PCB 516 (FIG. 5) for example, and their digital outputintegrated into the computation occurring in the locator CPU circuitry.It will be appreciated that the digital output from a 9-axis inertialsensor package, for example, will greatly enhance the ability of thelocator to differentiate among locations when integrated with themoment-to-moment correlations of data from the light sensor array 802during the locate process.

In another aspect, the use of this combination of sensors with a utilitylocating receiver provides data which may be used to integrate locatedetections with maps, satellite images, and/or area photographs.

FIGS. 11A to 11D illustrate example embodiments of perimeter opticalsensor arrays that may be used in various ground or surface trackingdevices. In addition to these example embodiments, other embodiments ofperimeter sensor array assemblies of various shapes, sizes, numbers ofsensors, and arrangement of sensor elements may be used in alternateimplementations. In general, perimeter optical sensor arrays includesensor elements covering all or substantially all of a peripheral areaof the sensor, such as around the perimeter of a circular, rectangle,triangle, oval, or other-shaped area. In some embodiments, someadditional interior sensor elements may also be used to enhanceprocessing performance and/or functionality, such as by providing sensedoptical values as particular positions in the interior of the array (inaddition to the sensed perimeter values). In addition, in someembodiments, grid-type sensor arrays may be used to provide similarfunctionality by selecting, measuring, and processing signals frompixels around the perimeter of the array while omitting use of all orsome of the interior pixel measurements on the array. For example, pixelvalues from pixels on the perimeter of a square or rectangular sensingelement may be used, optionally along with some interior pixel values,while the remaining values may be either ignored, discarded, or notcollected or sent from the sensor element to a processing element,

Turning to FIG. 11A, an example embodiment 1100A of a perimeter opticalsensor array is illustrated. Sensor array 1100A may include a substrate1110A, such as a printed circuit board integrated circuit device, MEMSdevice, or other substrate element on which individual sensor elements1120A may be disposed or integrated on or within. In an exemplaryembodiment, individual sensor elements 1120A may be sensor devices suchas Texas Advanced Optoelectronic Solutions (TAOS) sensor elements asdescribed with respect to FIG. 15, or other optical sensor elements. Inthe exemplary perimeter optical sensor array embodiment 1100A shown inFIG. 11A, the sensor elements are arranged around the perimeter of thesubstrate along the circumference and are radially aligned relative tothe center of the substrate. This configuration allows for the tightestpacking of sensor elements such as the TAOS elements, however, othersensor arrangements, such as sensors oriented in the same X, Ydirection, or in other arrangements, may alternately be used in someembodiments.

FIG. 11B illustrates another embodiment 1100B of a perimeter opticalsensor array, in this case in a square/rectangular configuration. Sensorarray 1100B may similarly include a substrate 1110B, such as a printedcircuit board integrated circuit device, MEMS device, or other substrateelement on which individual sensor elements 1120B may be disposed orintegrated on or within in a square/rectangular configuration such asshown. In an exemplary embodiment, individual sensor elements 1120B maybe sensor devices such as Texas Advanced Optoelectronic Solutions (TAOS)sensor elements as described with respect to FIG. 15, or other opticalsensor elements. In the exemplary perimeter optical sensor arrayembodiment 1100B shown in FIG. 11B, the sensor elements are arrangedaround the perimeter of the substrate along the edges and are aligned inthe same fashion relative to the outer edge of the square or rectangle.However, other sensor arrangements, such as sensors oriented in the sameX, Y direction, or in other arrangements, may alternately be used insome embodiments.

FIG. 11C illustrates yet another embodiment 1100C of a perimeter opticalsensor array, in this case in a triangular configuration. Sensor array1100C may similarly include a substrate 1110C, such as a printed circuitboard integrated circuit device, MEMS device, or other substrate elementon which individual sensor elements 1120C may be disposed or integratedon or within in a triangular configuration such as shown. In anexemplary embodiment, individual sensor elements 1120C may be sensordevices such as Texas Advanced Optoelectronic Solutions (TAOS) sensorelements as described with respect to FIG. 15, or other optical sensorelements. In the exemplary perimeter optical sensor array embodiment1100C shown in FIG. 11C, the sensor elements are arranged around theperimeter of the substrate along the edges and are aligned in the samefashion relative to the outer edge of the triangle. However, othersensor arrangements, such as sensors oriented in the same X, Ydirection, or in other arrangements, may alternately be used in someembodiments.

FIG. 11D illustrates yet another embodiment 1100D of a perimeter opticalsensor array, in this case in a circular configuration similar to thatof FIG. 11A while having additional rows of circumferentially arrangedsensor elements 1120D. Sensor array 1100D may similarly include asubstrate 1110D, such as a printed circuit board integrated circuitdevice, MEMS device, or other substrate element on which individualsensor elements 1120D may be disposed or integrated on or within in acircle such as shown. In an exemplary embodiment, individual sensorelements 1120D may be sensor devices such as Texas AdvancedOptoelectronic Solutions (TAOS) sensor elements as described withrespect to FIG. 15, or other optical sensor elements.

In the exemplary perimeter optical sensor array embodiment 1100D shownin FIG. 11D, multiple rows of the sensor elements are arrangedconcentrically around the substrate along the edges in a radialorientation as shown. However, other sensor arrangements, such assensors oriented in the same X, Y direction, or in other arrangements,may alternately be used in some embodiments. Similar configurationshaving multiple rows of sensors may be implemented based on thesquare/rectangular or triangular configurations shown in FIGS. 11B and11C, and/or in other shaped perimeter arrays. In addition, in someembodiments, additional interior sensor elements may be included, suchas reference sensor elements at the center or other reference points orareas within the sensor array. Use of additional sensor elements mayincrease processing demand by requiring additional corrections; however,additional sensors may be able to provide further information for use indetermining motion, location, and position data.

FIG. 12 illustrates details of an embodiment of a process 1200 fordetermining motion and/or position information in an optical groundtracking apparatus such as described herein. At stage 1210, the trackingprocess may be initiated, for example automatically based on locator orother device inputs, or by operator actuation, or continuously. Uponinitiation, an initial sample of light values at a plurality of sensorelements of a perimeter optical sensing array, such as the arrays shownin FIGS. 11A-11D, may be taken at stage 1214. During operation,additional samples may be taken either periodically or at an adjustablerate, as described further below.

After a sample is taken, a time delay interval may be done at stage1218. The time delay may be fixed or, in some implementations, variable,depending on other parameters such as device motion, groundcharacteristics, and the like. At stage 1222 another sample of sensorelement values of the perimeter sensor array may be taken. After theadditional sample is taken, a decision stage 1226 may optionally beimplemented, wherein a decision may be made as to whether there aresufficient samples to process. If not, processing may return to stage1218 where another delay may be done and stage 1222 where another samplemay be taken.

At stage 1230, one or more sets of samples may be cross-correlated, suchas in a processing element as described herein. For example, theprevious sample may be cross-correlated, wherein values corresponding toeach sensor element may be correlated with values of other sensorelements of the perimeter sensor array to determine a correlationresult. Alternately, or in addition, samples from two or more sets ofsamples may be cross-correlated.

For example, for a single sample set, if the perimeter array has 10sensor elements, the illumination and/or color values for sensor 1 maybe cross-correlated with those of sensors 2 through 9 to generate acorresponding correlation matrix (along with cross-correlations betweenthe other sensors as well). Further, when another sample is taken, thevalues for sensor 1 of the current sample may be correlated with thevalues of sensor 1 from previous samples, along with the values fromother sensors from the previous sample, to generate a time and positioncross-correlation matrix. This may then be used to determine relativemotion of the ground tracking apparatus across the surface, such as byidentifying when particular ground or surface features cross theperimeter of the perimeter sensor array based on correlation values.

In addition, motion, location, and/or position information 1235 may befurther processed at stage 1240 by combining optically sensed valueswith values from other sensing elements such as inertial sensors such asaccelerometers, compass sensors, GPS modules, wireless location modules,or other sensing elements or devices. At stage 1244, the determinedmotion, position, and/or location information may be stored in a memory,such as in a discrete memory or within a processing element.

In a typical operation, tracking will be repeated periodically, however,a decision stage 1250 may be included to determine whether to continuetracking and associated processing. If so, processing may be returned tostage 1218 or stage 1222 to collect further samples from the perimetersensor array. Alternately, if tracking is to be stopped, eitherautomatically or by user input, processing may be terminated after stage1250.

In some implementations, sampling may be dynamically controlled, such asbased on determined motion, ground characteristics, or other parameters.In this case, a time delay control input 1217, for implementing adaptivesample timing adjustment, may be provided to the time delay stage 1218(and/or to other intermediate stages) to control relative timing betweensample collection and/or correlation processing at stage 1230.

FIG. 13 illustrates details of an embodiment 1300 of an optical groundtracking apparatus in accordance with certain aspects. In operation,ground tracking apparatus 1300 may be coupled to a buried object locatoror other device, electrically and/or mechanically. For example,apparatus 1300 may be coupled electrically via connection 1372 to buriedobject locator electronics 1370 which may include various electronicmodules to process electromagnetic signals received from buried orhidden objects and generate depth information and/or other position orlocation information, such as described in the incorporatedapplications.

A ground or other surface area 1305 may be sensed such as by directinglight 1306 coming from the surface, either ambient, controlled outputlight from the ground tracking apparatus, or both, through optics 1310,which may be reflective and/or refractive optics, to further direct thelight 1312 to a perimeter optical sensor array 1320. Perimeter opticalsensor array 1320 may then sense the received light and generate acorresponding output signal, typically in the form of a digital outputsignal representing light characteristics at the perimeter sensor arrayoptical elements such as brightness and/or color or wavelength range.

For example, a sample of light output may be converted to an outputsignal representing a plurality of optical element values for brightnessand color at the individual optical elements disposed around theperimeter optical sensor. In some embodiments, the perimeter sensorarray may be configured to automatically combine output values frommultiple optical elements, whereas, in other embodiments an outputsignal multiplexing/conditioning electronics module 1326 may receivesignals from the multiple optical elements of the perimeter array andgenerate an output signal representing received light values for aparticular sample time.

The multiplexed output signal from the perimeter sensor array may thenbe provided via connection 1328 to a processing element 1330, where itmay then be processed as described herein, for example bycross-correlating sensor values within a particular sample time and/orcross-correlating sensor values across sample times.

In some embodiments, controlled illumination of the surface 1305 beingsensed may be provided. The controlled illumination may be done incoordination with the sampling of received light at the perimeter sensorarray 1320. For example, a light source 1380, such as a laser LED orother device, which may be combined with a diffraction grating or othermechanism, may direct controlled illumination to the target. Asdescribed previously herein, this may be in the form of lines or othershapes across the ground surface 1305. These may be further pulsed orotherwise cycled to facilitate detection and processing. A light outputcontrol electronics module 1382 may be used to control, via connection1384 to the light source 1380 and connection 1332 to the processingelement, output from the light source 1380. In some embodiments thelight control functionality may be implemented entirely or substantiallywithin the processing element, however, in other embodiments separatelight control circuitry, such as circuit module 1382 as shown, may beused to control light output.

In addition, position and/or motion sensing elements, such asaccelerometers, compass sensors, GPS or other devices, wireless-basedposition or location sensing devices, and the like may be used toprovide additional motion, position, and/or location information to theprocessing element. For example, a motion sensing device may be used togenerate motion information to be provided via connection 1352 to theprocessing element, which may then use this information to adjustparameters related to the sensing being performed at the perimetersensor array 1320. This may be directly by the processing element and/orin conjunction with additional circuitry such as a sensor power/controlcircuit module 1322 as shown, which may be coupled via connection 1334to the processing element 1330. Similarly, one or more connections 1352may be used to couple the position/motion sensors to the processingelement 1330.

In one example configuration, motion and position data may be generatedat sensor(s) 1350 and sent to processing element 1330, where they may beused to control the speed of sampling at the perimeter optical sensor.For example, if the motion information indicates that the groundtracking apparatus is moving relatively slowly across the ground, thesampling and associated correlation processing may be sped up so as tocapture cross-correlations as the ground surface moves across theperimeter array sensor elements. Conversely, if the ground trackingapparatus is moving relatively fast across the ground, sampling may bedecreased since the ground surface will be moving more slowly across theperimeter array sensor elements. Similar information may be used todetermine changes in direction, speed, and the like and may be fed backto the processing element to adjust sampling and/or correlationprocessing accordingly. In addition, controlled light output, such as inthe form of lines or other shapes, which may be pulsed, may be generatedat light source 1380 and directed to the surface area, where sampling atthe perimeter sensor array may be coordinated with the light output soas to determine parameters such as tilt of the apparatus or ground,relative height above the ground, and the like.

FIG. 14 illustrates details of an embodiment 1400 of an alternateoptical assembly for providing light from the ground or another surfaceto a perimeter optical imaging sensor, such as sensor 1422 as shown.Optical assembly 1400 includes a housing assembly 1410 for mounting oneor more refractive elements within, such as objective lens 1418 asshown. Other embodiments may use any of the variety of refractive lenselements and lens element configurations as are known or developed inthe art to direct light using refraction to an imaging sensor. Forexample, rays 1414 and 1412 from the ground surface may be incident onlens 1418 as shown and may be bent as shown in lens element 1418 togenerate a real image on the plane of the sensor 1422.

Sensor 1422 may be positioned on a mounting assembly within the housing,such as mounting bracket 1402 as shown, or on other mounting mechanism.Other elements (not shown in FIG. 14) may be included in embodiments ofoptical assemblies, such as focusing elements, panning or zoomingelements, aperture control elements, tilt elements, and/or othermechanical or optical adjustment mechanisms.

In operation, incoming light from the ground or other surfaces (asillustrated by rays 1412 and 1414) enter optical assembly 1400 throughobjective lens 1418 and are directed to perimeter optical sensor array1422 where they are then captured by ones of a plurality of opticalsensor elements of optical sensor array 1422, with the sensor outputsthen provided to a processing element (not shown) for correlationprocessing, similarly to the examples described previously herein withrespect to reflective optical assemblies.

FIG. 15 illustrates details of an exemplary optical sensor element 1520as may be used in various embodiments of perimeter optical sensor arraysin ground tracking devices as described herein. Sensor element 1520corresponds with a commercially available embodiment in the form of aTexas Advanced Optoelectronic Solutions (TAOS) TCS 3304 or TCS 3414digital color sensor as described in, for example, the TAOS197A-APRIL2011 datasheet, the content of which is incorporated by referenceherein.

In this device, multiple photodiodes with corresponding filters,analog-to-digital converters, and associated control electronics areincorporated to provide 16 bit resolution digital color chromaticity andilluminance (intensity) of received light. As shown in FIG. 15, each ofthe circuit blocks 1524 of the sensor element 1520 includes aphotodiode, filter (denoted as R for red, G for green, B for blue, and Wfor clear or no filter). These photodiodes are configured in amulti-color sensing array 1522 to combine outputs from the variousphotodiodes to generate the 16 bit output data. In addition, the sensingelement can be synchronized with an external light source, such as alaser LED or other light source, to support the controlled illuminationfunctionality described herein. It is noted that while TAOS sensorelements may be used in one exemplary embodiment, various otherintegrated or distributed sensor devices having monochrome and/or colorlight sensing functionality, in either infra-red, visible light, orultraviolet wavelengths may be used in alternate embodiments.

In some configurations, the apparatus, circuit, modules, or systemsdescribed herein may include means for implementing features orproviding functions described herein. In one aspect, the aforementionedmeans may be a module comprising a processing element including aprocessor or processors, associated memory and/or other electronics inwhich embodiments of the invention reside, such as to implement signalprocessing, switching, transmission, or other functions to processand/or condition transmitter outputs, locator inputs, and/or provideother electronic functions described herein. These may be, for example,modules or apparatus residing in buried object transmitters, locators,coupling apparatus, and/or other related equipment or devices.

In one or more exemplary embodiments, the electronic functions, methodsand processes described herein and associated with sensors and locatorsmay be implemented in hardware, software, firmware, or any combinationthereof. If implemented in software, the functions may be stored on orencoded as one or more instructions or code on a computer-readablemedium. Computer-readable media includes computer storage media. Storagemedia may be any available media that can be accessed by a computer. Byway of example, and not limitation, such computer-readable media cancomprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage,magnetic disk storage or other magnetic storage devices, or any othermedium that can be used to carry or store desired program code in theform of instructions or data structures and that can be accessed by acomputer. Disk and disc, as used herein, include compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.

As used herein, computer program products comprising computer-readablemedia include all forms of computer-readable medium except, to theextent that such media is deemed to be non-statutory, transitorypropagating signals.

It is understood that the specific order or hierarchy of steps or stagesin the processes and methods disclosed herein are examples of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of steps in the processes may be rearrangedwhile remaining within the scope of the present disclosure unless notedotherwise.

Those of skill in the art would understand that information and signals,such as video and/or audio signals or data, control signals, or othersignals or data may be represented using any of a variety of differenttechnologies and techniques. For example, data, instructions, commands,information, signals, bits, symbols, and chips that may be referencedthroughout the above description may be represented by voltages,currents, electromagnetic waves, magnetic fields or particles, opticalfields or particles, or any combination thereof.

Skilled artisans may implement the described functionality in varyingways for each particular application, but such implementation decisionsshould not be interpreted as causing a departure from the scope of thepresent disclosure.

The various illustrative functions and circuits described in connectionwith the embodiments disclosed herein may be implemented or performed ina processing element with a general purpose processor, a digital signalprocessor (DSP), an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) or other programmable logic device,discrete gate or transistor logic, discrete hardware components, memorydevices, and/or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The steps or stages of a method, process or algorithm described inconnection with the embodiments disclosed herein may be embodieddirectly in hardware, in a software module executed by a processor, orin a combination of the two. A software module may reside in RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, harddisk, a removable disk, a CD-ROM, or any other form of storage mediumknown in the art. An exemplary storage medium is coupled to theprocessor such the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium may be integral to the processor. The processor and the storagemedium may reside in an ASIC. The ASIC may reside in a user terminal. Inthe alternative, the processor and the storage medium may reside asdiscrete components in a user terminal.

The presently claimed invention is not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the specification and drawings, wherein reference to an element inthe singular is not intended to mean “one and only one” unlessspecifically so stated, but rather “one or more.” Unless specificallystated otherwise, the term “some” refers to one or more. A phrasereferring to “at least one of” a list of items refers to any combinationof those items, including single members. As an example, “at least oneof: a, b, or c” is intended to cover: a; b; c; a and b; a and c; b andc; and a, b and c.

The previous description of the disclosed aspects is provided to enableany person skilled in the art to make or use embodiments of thepresently claimed invention. Various modifications to these aspects willbe readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other aspects withoutdeparting from the spirit or scope of the disclosures herein. Thus, thepresently claimed invention is not intended to be limited to the aspectsshown herein, but is to be accorded the widest scope consistent with theappended claims and their equivalents.

We claim:
 1. A method for tracking motion of a buried utility locatorwhile being moved over a ground surface by a user, comprising: sensingmagnetic fields emitted from a buried utility in a magnetic fieldsensing antenna array of the locator at two or more locations;processing the sensed magnetic fields to generate buried utilityinformation associated with the buried utility in a processing elementof the locator at the two or more locations; detecting, at the two ormore locations, light reflected from the ground surface; computing auser-effected motion of the buried object locator over the groundrelative to a tracking ground surface between the two or more locationsat least in part based on analysis of light patterns associated with thetracking ground surface; generating motion information correspondingwith the computed user-effected motion; combining the buried utilityinformation with the motion information; and storing the combined buriedutility information and the motion information in a non-transient memoryof the locator.
 2. The method of claim 1, wherein the light reflectedfrom the ground surface is detected by a sensor array.
 3. The method ofclaim 2, wherein the sensor array is a rectangular optical sensor array.4. The method of claim 3, wherein the rectangular optical sensor arrayincludes two or more rows of optical sensor elements.
 5. The method ofclaim 4, wherein the optical sensor elements are color sensor elements.6. The method of claim 2, wherein the sensor array is a circular opticalsensor array.
 7. The method of claim 2, wherein the sensor array is asingle row optical sensor array.
 8. The method of claim 2, wherein theoptical sensor array includes a plurality of sensor elements.
 9. Themethod of claim 8, wherein the sensor elements are color sensorelements.
 10. The method of claim 1, wherein the light reflected fromthe ground surface is detected by a camera.
 11. An apparatus fortracking motion during a locating process while being moved over aground surface by a user, comprising: a buried utility locatorincluding: an antenna array for sensing magnetic fields emitted from aburied utility in a magnetic field sensing antenna array of the locatorat two or more locations; and electronics, including a receiver circuitoperatively coupled to the antenna array and a processing element, forprocessing the sensed magnetic fields to generate buried utilityinformation associated with the buried utility at two or more locations;an electronic circuit, including a sensor array, for: detecting, at thetwo or more locations, light reflected from the ground surface;computing a user-effected motion of the buried object locator over theground relative to a tracking ground surface between the two or morelocations at least in part based on analysis of light patternsassociated with the tracking ground surface; and generating motioninformation corresponding with the computed user-effected motion. 12.The apparatus of claim 11, wherein the buried utility information iscombined with the motion information, and the combined information isstored in a non-transient memory.
 13. The apparatus of claim 11, whereinthe sensor array is a rectangular optical sensor array.
 14. Theapparatus of claim 11, wherein the rectangular optical sensor arrayincludes two or more rows of optical sensor elements.
 15. The apparatusof claim 14, wherein the optical sensor elements are color sensorelements.
 16. The apparatus of claim 11, wherein the sensor array is acircular optical sensor array.
 17. The apparatus of claim 11, whereinthe sensor array is a single row optical sensor array.
 18. The apparatusof claim 11, wherein the optical sensor array includes a plurality ofsensor elements.
 19. The apparatus of claim 18, wherein the sensorelements are color sensor elements.
 20. The method of claim 11, whereinoptical sensor array comprises a camera.